The new plugin list is based on the ones currently used in our ember-cli pipeline, and are based on our official browser support policy.
This commit includes an update to the raw-handlebars compiler to remove the 'very hacky but lets us use ES6' code. It's served us well for the last 6 years, but the babel config changes broke it (`const` -> `let`). This commit takes the opportunity to refactor it to take a similar approach to PrettyText, by leaning on `mini-loader.js`.
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